If your hack, like Parallel Worlds, does not force a dungeon order, and could potentially allow getting the red tunic upgrade before the blue, and you'd like to stop the player from skipping an upgrade, you can achieve this by placing blue tunics in both chests (assuming both armors are retrieved from chests, if you want to give them to the player in another manner, this may not work), and then setting the blue tunic alt treasure to red tunic. Then, no matter which one the player collects first, they will always get the blue tunic first, then red.